The present invention relates to a coil device which is provided with a plurality of winding drums on a bobbin with a partition formed between flanges at both ends of the bobbin.
A coil device which is formed by winding a coil around a bobbin is often used to generate a magnetic force (e.g., a solenoid, a magneto coil or the like) or to detect a magnetic flux (e.g., a detector for detecting the number of revolutions of a distributor type pump or the like).
As shown in FIG. 6, generally, a coil device 1 of the type described above has a partition 5 formed between flanges 3, 4 at both ends of a bobbin 2 to provide a plurality of winding drums 6, 6 on the bobbin 2. The shape of bobbin of the coil device 1 is often determined depending on output characteristics or limitations in the system. Especially, it is known that when a thickness t of the partition 5 is increased, the coil has a long overall length, and it becomes difficult to make it compact. It is also known that the output sensitivity in the output characteristics is lowered. Therefore, the thickness t of the partition 5 cannot be made large.
In the coil device 1 having the plurality of winding drums 6, 6 on the bobbin 2 of the above-described prior art, a slit 7 is formed in the partition 5. A wire w is arranged from one of the winding drums 6, 6 to the other through the slit 7. In FIG. 6, reference numeral 8 denotes a slit of the flange 3, reference numeral 9 denotes a terminal mount, and reference numerals 9a, 9b, 9c denote terminals.
As described above, the partition 5 of the small coil device 1 has a thickness t of about 1 mm because the thickness t of the partition 5 can not be made thick. When the partition 5 has the thickness of about 1 mm, a corner 7a of the slit 7 has a radius of about 0.5 mm. When an ordinary wire w having a diameter of 0.09 mm is passed around the corner 7a, the wire w has a bending diameter of (5xc3x97 a wire diameter) at the corner 8a. Thus, the wire is bent acutely to concentrate a stress on the bent portion, possibly resulting in a breakage of the wire.
The present invention was achieved in view of the aforesaid situation. Thus, the present invention is to provide a coil device which can make the wire bend in the slit of the partition as small as possible to prevent the wire from being broken and to have an improved reliability, without making the bobbin in any special structure.
The invention recited in claim 1 is a coil device which has a plurality of winding drums on a bobbin with a partition formed between flanges at both ends of the bobbin, wherein the partition has a slit through which a wire is passed, and of winding pitches of the wire wound on adjacent winding drums with the partition therebetween, at least a pitch between a segment of the wire passing through the slit and its adjacent segment of the wire is larger than a pitch between the segments of the wire at other portions.
Thus, when the pitch between the wire segment passing through the slit and its neighboring wire segment is larger than the pitch between other wire segments, the wire segment passing through the slit of the partition has a large angle with respect to the partition. As a result, the wire can be prevented from being bent acutely at the corner of the slit and becomes free from a stress, so that its breakage can be prevented and the reliability can be improved.
The invention is a coil device which has a plurality of winding drums on a bobbin with a partition formed between flanges at both ends of the bobbin, wherein the partition has a slit through which a wire is passed, and the slit and a slit of each flange are displaced from each other by a predetermined angle with respect to the center of a winding so that the segments of the wire passing through the slits are angled with respect to the center of the winding.
Thus, when the positions of the slit and that of the flange are displaced by the predetermined angle with respect to the center of the winding to angle the wire segments passing through both slits with respect to the center of the winding, so that the wire segment passing through the slit of the partition has a large angle with respect to the partition in the same way as in claim 1. Therefore, the wire can be prevented from being bent acutely at the corner of the slit and free from a stress. Accordingly, the wire can be prevented from being broken and the reliability can be improved. Here, the predetermined angle depends on a length of the bobbin and particularly on an interval between the slits. Preferably, it is about 90 degrees for the compact coil device.
The invention is a coil device which has a plurality of winding drums on a bobbin with a partition formed between flanges at both ends of the bobbin, wherein the partition has a slit through which a wire is passed through, and a one-side radiused portion is formed at an end of the slit with which the wire passing through the slit is slidably in contact.
Thus, when the one-side radiused portion is formed at the slit end, the radiused portion can be made to have a considerably large curvature as compared with the formation of a both-side radiused portion at the slit end, so that the wire can be prevented from being bent acutely at the slit corner and becomes free from a stress. Therefore, the wire can be prevented from being broken and the reliability can be improved.